SPDL1 and melanoma: In particular, no statistically significant association between sPD-L1 levels and PFS was obtained in the RCC group with an HR = 0.59 (0.13–2.66, p = 0.49, I2 = 83%, Figure S2) and in the melanoma patients with an HR = 1.16 (95% CI:0.65–2.08, p = 0.62, I2 = 52%, Figure S3).